The present invention relates to a washing agents dispenser device, particularly developed for dishwashing machines, as described in the preamble of the claim 1, and actuation method thereof.
Dishwashing machines, in particular household dishwashers, usually employ dispenser devices for dispensing washing agents, which are normally housed in the dishwasher inner door.
Devices capable of dispensing different types of washing agents, such as detergent and rinse aids, are widely spread. These devices are provided for dispensing the detergent and rinse aids at different pre-set times, being their operation controlled by an appropriate programmer or timer of the dishwashing machine.
The use of a well defined type of dispenser devices as illustrated, described and taught in the U.S. Pat. No. 5,884,821 or European Patent No. EP 0780087 B1 is already known. These documents disclose a dispenser device as shown in the annexed FIGS. 1-4, globally indicated with reference number 1, which consists of a body 2 comprising and/or incorporating the following parts:                a compartment 4 for containing a washing agent;        a sliding cover 5 from a closed position to an open position of the above compartment 4;        locking/release means 8, 10, 11, 12, 13, 14 related to the sliding cover 5, which are associated to an appropriate actuator for releasing the cover 5, said elements being only partially apparent in the above figures;        a rinse-aid or liquid washing agent dispenser 3.        
In particular, the opening of the sliding cover 5 is controlled by common elastic or thrusting means 14, such as an appropriately constrained cylindrical helical spring; the sliding cover 5 has extensions 17A and 17B restraining it to matching sliding guides 16, 18, 19, 20, 21 provided in the body 2, which are configurated for guiding it along translations that follow a mainly straight path.
Reference is made to the above documents for further specifications of such a device known to the technical state of art, such as a complete set of figures rather than a detailed description or its operation.
Special attention is paid to the operation of the dispenser device 1 for closing the compartment 4, which is performed manually by the user of the dishwashing machine. Actually, in order to start a wash cycle, at the beginning of each wash cycle the user has to return the sliding cover 4 to its closed position after loading the washing agent in the compartment 4.
Performance of this operation is not quite simple and immediate, since when the operator slides the sliding cover 5 to its closed direction, the latter will be engaged at translation end, i.e. with the front relief 17A reaching the lead-in location of the step guide 18, with its rear relief 17B in line with the rise of the inclined plane 20 related to the lead-in guide 19. Further in its guided movement, the rear relief 17B will rise on the inclined plane 20 and the sliding cover 5 take a slightly inclined position. Then the front relief 17A slides on the joining inclined plane of the step guide 18 downwards, i.e. putting the front side of the gasket 15 in contact with the first sealing edge 4A′, i.e. the one facing the dispenser 3, whereas the rear side lifts up. When the relief 17B exceeds the inclined plane 20 entering the depression of the lead-in guide 19, also the rear side of the sliding cover 5 goes downwards, bringing the lower side of the gasket 15 in contact with the second sealing edge 4A″. The above details are clearly illustrated in the FIGS. 3 and 4, where the sliding cover 5 is shown in its closed position.
Once the inclined plane 20 has been exceeded, a mutual coupling between the tooth 10 of the hooking element 8 and tooth 11 of the cover 5 occurs as described hereafter, so the cover will be hooked in its closed position.
The sliding cover 5 moves for a length according to a substantially plane motion, over a substantially straight path. When the rear relief 17B is in line with the rise of the inclined plane 20, the sliding cover 5 moves on inclined planes with respect to the motion plane identified by the substantially plane motion. At the end of the above movement, the sliding cover 5 practically requires a slight pressure in orthogonal way to the motion plane, favouring the engagement between the gasket 15 and sealing edges 4A and 4B, i.e. the closure of the compartment 4 by interposition of an elastic seal. Finally, in order to ensure a final locking or hooking in the closed position, the user should further pull the sliding cover 5 to for another very short length along the substantially straight path, minding to keep it pressed towards the dispenser, i.e. keeping the gasket 15 pressed over the edges 4A and 4B for facilitating a housing of the front relief 17A in the horizontal development of the step guide 18, as highlighted in FIG. 4.
According to experience, a closure of the sliding cover 5 according to the above procedure is not immediately guessed by the users of dishwashing machines, who generally perform more than one operation in the attempt of hooking the cover in its closed position. When closing the cover 5, these users do not pull the cover 5 to up to its complete engagement between the teeth 10 and 11, forgetting to press the cover 5 towards the compartment 4 and further pull it straight to for its short final length before hooking.
Performing just an intuitive translation movement, i.e. pulling to according to the straight closure path, without appropriately guiding or directing the cover as described above, difficulties may arise in closing and/or hooking the cover correctly.
If the cover does not close, it is obviously impossible to use the household appliance correctly; the same applies in the verifiable instance of a faulty hooking of the cover 5, which may open before the time set by the timer of the dishwashing machine and cancel the washing efficiency of the subsequent wash cycle, which will be performed without detergent.
A further drawback due to the above difficulty of hooking the cover for its closure may be a possible damage to the relieves or other parts of the dispenser, should the user strongly force the movement of the cover to other directions and following different procedures than described.
Other types of washing agents dispensers, such as multi-charge dispensers fitted with linear or angular movable covers, are provided with the compartment for containing the washing agent or washing agents sealed by closing the cover on the main body. To this purpose, an interference between the contacting seal elements will cause a mutual rubbing during the opening and closing operations of the cover. The above seal elements are arranged on the dispenser main body and on the movable cover to have them mutually compressed one upon the other when in contact. These sealing elements mainly comprise a sealing gasket, which may be integral to the body or cover, and an element on which the above gasket is maintained pressed, such as compartment edges.
The seal elements of these dispensers may be subject with time to abrasions due to their mutual rubbing with subsequent loss of the gasket sealing capacity, such a phenomenon being higher in the instance of possible solid detergent rests on the seals.